In the field of integrated circuit (IC) devices, reliable connections between different components are essential for correct functioning. In order for an IC device to be able to correctly function in relation to an external component, each connection within a signal path between the semiconductor die of the IC device and the external component must be reliable and intact, i.e. not broken. In the case of safety devices, this issue is of particular importance, since a single broken connection can result in a complete failure of the device or the system it is integrated into. For example, the root cause of such a failure may be a broken connection to an input device such as a sensor or a broken connection to an output device such as a unit controlling a motor. Thus, ensuring the reliability of connections is of major importance for safety devices.
Conventionally, this may be achieved through the use of redundant connections. However, a problem with this technique is that it requires the number of input/output pads/contacts to be substantially doubled. Since the number of input/output pads/contacts within an IC device is limited, and their availability typically at a premium, this doubling requirement is clearly undesirable.
Alternatively, the reliability of connections may be increased by repeating the corresponding input/output operations. For example, data signals may be transmitted twice, and the two versions of the transmitted data are compared in order to identify the presence of broken connections. However, a problem with this technique is that it requires specific transmission protocols or a specific functionality on the device boundary or within the transmitting or receiving device that is aware of this replication. Accordingly, such a technique increases the signalling complexity and other overheads.
Alternatively still, other means outside of the IC device may be used to determine the reliability of connections. However, a problem with this technique is that it requires specific external hardware to observe the IC device and its connections, thereby increasing the cost and real estate requirements of the system.